Reattach with flaky retry triggers unwanted identity request

[VinashakAnkitAman]

Setup Details

The S1APTester was used along with Magma EPC (https://github.com/magma/magma) to generate the issue.

Summary:

It has been observed that in any test case if after receiving the attach accept, test case fails without sending the attach complete, the test case fails in retry also where after sending the attach request it expects authentication request, but receives the identity request. the reason is that the testcase sends attach request which is integrity protected for the 2nd time and leads to trigger of identity request from MME.

Steps to Reproduce
Enable flaky retry and modify any test case to fail after receiving attach accept for the first time. The retry attempt will fail with the above reason. This is one example from the CI run: https://storage.googleapis.com/magma-ci.appspot.com/lte_integ_test_d43c5770803f2e7da9a78b6df968b4e0c06f3a2f.html